For an objective lens of a microscope, a high numerical aperture has always been demanded in order to improve resolution and brightness during fluorescent viewing, and good correction of chromatic aberration is also required. However as numerical aperture increases, the depth of focus decreases and correction of chromatic aberration (including chromatic aberration due to spherical aberration) becomes difficult, and in order to solve this problem, many anomalous dispersion glasses must be used, which are expensive and difficult to process. Also picture elements, such as CCD and peripheral technology thereof, are advancing lately, and the purpose of a microscope is becoming more like an image input device rather than a conventional microscope for viewing samples using an eye piece. In this case, an obtained image is preferably flat and uniform throughout the entire field of view. In this situation, today various objective lenses using diffractive optical elements are being proposed in order to correct chromatic aberration in an advanced way (e.g. see Patent Document 1).    Patent Document 1: Japanese Laid-Open Patent publication No. H06-331898
A problem of this objective lens, however, is that various aberrations throughout the entire field of view cannot be sufficiently corrected to be used for a microscope.